Sound damped muffler



Patented Aug. 2, 1932 PATENT QFFEE FRANCIS F. HAMILTON, OF INDIANAPOLIS, INDIANA SOUND DAMPED MUFFLER No Drawing.

This invention relates to the art of exhaust mufilers for gas engines and particularly to means for reducing noise arising from vibration and impinging of gases against the walls.

Heretofore it has been customary to form muffler structures with a variety of gas passages therethrough intended to receive and conduct the gases in such manner that .10 through expansion, variable lengths of travel, reflection, and the like, much of the noise of the individual explosions was eliminated, but in spite of whatever structure was employed, an objectionable noise remained due largely to the direct impinging against the various walls of the muffler and also to vibrations arising about orifices as the gases escaped therethrough.

The primary objects of the invention re- 2 side in so covering surfaces within the muffler that no noise will be discernible therefrom; in providing a method for covering the walls that is very readily and quickly accomplished; and in employing material that is easily obtained, easily handled, and

that is relatively very low in cost.

Other objects reside in the durability and permanence of the finished surface, and in obtaining the desired result Without increase in weight of the mufiler.

I take water glass (usually sodium silicate) as supplied in commerce dissolved in Water as a sirupy liquid and coat inner walls of the muffler with it around orifices and at points where the gases would impinge when being changed in direction of flow or upon leaving passageways, and the like. I find that the coating of such areas only is suflicient and that it is not necessary to coat the entire inner surfaces although there is no objection to doing sobeyond the additional cost of time and material.

of the gases Application filed July 26', 1929. Serial No. 381,408.

direct contact with the water glass which has dried on the various coated areas.

The exposure of the water glass to these heated gases results in changing the form of the transparent water glass to a foaming 55 mass which quickly solidifies upon evaporation of the water and clings tenaciously to the metal surface. The solidified mass has a very irregular roughened surface exposed to the gases, and the interior is cellular. It m) has been found that this coating of heated water glass remains in place even under prolonged periods of operation of the muffler and that it is extremely effective in eliminating vibrations of the muffler wall.

I claim: I

1. The method of producing a sound damped, metallic exhaust muliler comprising coating a surface of the muffler with a silicats in solution and rapidly driving off the 7 solvent by heat of the exhaust gas passing through the muffler.

2. The method of producing a sound damped, sheet metal exhaust gas muffler comprising coating a surface of the muffler with 75 Water glass and subjecting that surface to heat supplied by the exhaust gas passing through the muiiier.

3. The method of producing a sound damped, sheet metal exhaust gas muflier comso prising the forming of the sheet metal parts, coating the desired surfaces of the parts with water glass before closing the muffler in its manufacture, closing the muffler, and subjecting the coated surface to heat supplied by so the exhaust gas passing through the mufller.

In testimony whereof I affix my signature.

I FRANCIS F. HAMILTON.

Those areas above referred to are first coated before the muffler is closed up. The muffler is then assembled and placed in the automobile or other installation selected for its use and the gases from the engine whose exhaust is to be muflled are allowed to flow through the muffler. These gases carry con- 50 siderable heat from the engine and come into 

